Motor-pump unit



Sept. 26, 1933. F. D. PELTIER MOTOR PUMP UNIT Filed July 1'7, 1930 2 Sheets-Sheet 1 IN VEN TOR.

Sept. 26, 1933. L R

' MOTOR PUMP UNIT Filed July 17 1930 2 Sheets-Sheet 2 INVENTQR.

TORNEYS Patented Sept. 26, 1933 MOTOR-PUMP UNIT Frank D. Peltier, Evansville, Ind., assignor, by mesne assignments, to Servel, Inc., New York, N. Y., a corporation of Delaware Application July 17, 1930. Serial No. 468,679

8 Claims.

This invention relates to motor pump units for refrigerating systems, and more particularly to motor-pump units .for use in domestic refrigerating systems.-

The invention has for its object generally, an improved constructionand arrangement of parts for units of the character described, which is efficient, economical and readily manufactured.

More specifically, an object of the invention is to provide a rotary pump or compressor of the character described in which a lubricating system is employed, which keeps the pump blades at all times in gas-tight engagement with the walls of the pump chamber.

A further object is to provide a pump of the character indicated in which a supply of lubricant is constantly maintained back of the pump blades to prevent the entrance of gaseous vapors into the same, thereby increasing the efiiciency of the pump.

Still another object is to provide an improved lubricant-distributing system for rotary pumps and compressors, in which the lubricant is evenly forced to all parts in metered quantities.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the constructions hereinafter set forth and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a vertical sectional view through the axis of a motor pump unit, constructed in accordance with the invention;

Fig. 2 is an enlarged fragmentary sectional view showing details of the pump construction;

Fig. 3 is an enlarged view partly in section and partly in elevation taken on the line 3-3 of Fig. 2; and

Fig. 4 is a perspective view showing the pump blades employed in the present invention.

Referring now to the drawings, and particularly to Fig. 1, 10 denotes the cylindrical wall of a motor casing, the interior of which has a portion 11 of smaller bore than the main portion in order that it may be adapted to support frictionally the stator 12 of an electric motor having a rotor 13 secured on a shaft 14 which is rotatably mounted in the end walls of the cylindrical cas- This second casing has an inlet passage 20" arranged to communicate with a passage 21 formed in the center drive plate and with which a return connection 22 from an evaporator unit not shown in the interests of clearness) communicates on the exterior of the casing. This return connection includes a check valve 23 preferably provided after the manner disclosed in my co-pending application, Serial No. 429,280, filed February 18, 1930. An outlet connection leads from the upper part of the compressor casing, as shown at 24.

In the practice of the present invention, the pump or compressor is so constructed. that a supply of lubricant is readily forced to all moving parts of the pump and its motor, the arrangement being preferably such as to force a supply back of the pump blades as it passes a by-pass 40 shown in Fig. 2. To this end, a cover 25 is provided for the end of the compressor which has a hub 26 provided with a depending nozzle 27, the outer or lower end of which is preferably provided with a filter in the form of a screen, as indicated at 28, whereby strained working fluid is admitted to a small reservoir or distributing head .29 in the hub. This hub is also formed so as to comprise an extension of the bearing which houses an end 30 of the compressor shaft, the other end 31 being flexibly keyed into the motor shaft 14 as indicated at 32. The compressor shaft at an intermediate point has a disk 33 adapted to drive the pump blades shown generally at 34. This disk is preferably formed integrally with the compressor shaft, although it may be keyed or otherwise secured to this shaft.

The disk 33 is provided with substantially radial slots in which the blades 34 are adapted to reciprocate, the blades being arranged to bear against the interior wall of the cylindrical casing of the compressor 19.

As shown particularly in Figs. 2 and 3, it will be seen that the compressor shaft is disposed eccentrically in the cylindrical casing of the compressor 19, the disk 33 being displaced so as to have working engagement with an element 35 of the casing wall which is situated between the inlet opening 36 and an outlet opening 37 that are preferably formed as channels directly in the interior wall. The inlet channel 36 is indicated in Fig. 3 as having a relatively large circumferential extent and communicates with the inlet passage 20. This is arranged so that the relatively expanded gaseous medium comprising the refrigerant circulated by the compressor may be admitted in relatively large quantitles and freely taken up by the blades 34. The direction of the rotation for the disk 33 is shown by the arrow 11 in Fig. 3 which indicates counterclockwise rotation for the arrangement of disk here shown; thus as the blades sweep the expanded medium away from the inlet passage, it is progressively moved into a smaller and smaller space until it is finally swept into the region opposite the outlet opening 37 which is seen to be a channel having relatively smaller circumferential extent about the cylindrical wall.

The blades of the present invention are so constructed that they have a forward engaging edge 38 adapted at all times to bear snugly against the cylindrical wall of the compressor casing. The forward faces of the blades 34 are also provided with one or more grooves 39 which permit communication between the gas space ahead of the blades and the space behind the blades in the disk 33, thereby avoiding a vacuum look.

In order however to provide a positive pressure of relatively constant magnitude behind the blades 34, the compressor of the present invention is provided with means for supplying working fluid directly to the space behind the blades 34 in the disk 33. To this end, a by-pass is shown at 40 (see particularly Fig. 2) which leads from the reservoir 29 and is arranged to discharge directly into a space 41 behind a blade 34 when such blade has substantially its maximum displacement in the disk 33. This by-pass is conveniently provided by boring a channel in the hub 26 parallel to the axis of the bearing chamber and adapted to communicate with such space when the blades pass to their position of substantially maximum displacement. This occurs substantially in the position shown in Fig. 2 when a blade 34 has just closed the inlet passage 36. In Fig. 2, the space 41 communicates directly with the passage 40, so that the working fluid, which comprises in this instance both lubricant and refrigerant, flows through the nozzle 27 and thence through the by-pass 40 into the space 41. An exit for the working fluid from the space 41 is provided by forming an arcuate passage 42 in the wall of the centre drive plate about the bearing opening for the shaft end 31. This passage 42 extends radially a suflicient distance below the bearing opening to communicate with the top of spaces 41. A groove 43 in the bottom of the bearing passage in the centre drive plate communicates with the arcuate passage 42 and extends a sufficient distance to permit the working fluid to have free flow and entry at the joint between the shaft end 31 and the motor shaft 14, so that the working fluid may pass into a central passage 44 formed therein and leading along its axis to the outer motor bearing, discharging thereinto at a point wherea relatively low pressure prevails; such low pressure being obtained by reason of a by-pass connection, shown at 44', between the interior of the motor casing and the pump inlet passage 21.

In operation, it is seen that the pump or compressor 19 discharges into the casing 18 above the normal liquid level of the working fluid in the casing 18. The gaseous refrigerant is in consequence in a state of high compression above the liquid level 45 when the pump or compressor is in operation, whereas the suction in the passage 21 creates a relatively low pressure therein, so that there exists a relatively low pressure, communicated by passage 44, in motor casing 10; consequently there is a pressure differential between the interior of the casing 18 and the motor casing 10, or, more specifically, between reservoir 29 and passage 44. This pressure differential causes working fluid to flow up the nozzle 27 to the reservoir 29, a portion passing by groove 46 directly to the interior of the compressor. Another portion passes through the by-pass 40, and flows into each space 41 behind a compressor blade 34 as it passes the by-pass opening where it discharges into the compressor casing. At this point, the compressor blade has substantially its maximum displacement; hence the space behind it receives a relatively large amount of working fluid as soon as it reaches this point in its travel about the compressor casing. The supply of working fluid to the space 41 is immediately cut off, as soon as the space 41 moves out of communication with passage 40. In this manner, ameasured quantity of working fluid containing lubricant is regularly admitted to the space behind the compressor blades as they pass this point. It is seen also that this admission of working fluid produces a pressure in the space 41 which operates to hold the blade more firmly against the cylindrical wall than would be the case if gaseous agents were admitted through the passages 39 for this purpose.

As the blades move from the position of maximum displacement to the position of minimum displacement, the working fluid in the space 41 is gradually forced out, partly about the blade 34 whereby they become lubricated and partly through the passages 42, 43 and 44 into the motor casing.

A hydrostatic pressure is seen in consequence to operate to hold the blades in position against the cylindrical wall from the time that the blade has sealed off a charge of gaseous medium taken from the inlet until it is finally discharged into the outlet passage 37; the measured quantity of working fluid thus being forced into circulation discharges both a blade holding function and a lubricating function.

The gaseous medium thus compressed can at no time enter the space 41 behind the blades of the present compressor, which operates in consequence to increase the efficiency with which the compressor compresses the refrigerant. A sufflcient compression of gaseous refrigerant for all general refrigeration purposes is readily attainable with a compressor having but one stage when constructed in accordance with the present invention.

While a hermetically sealed motor-pump unit has here been shown in which a pressure differential exists between the motor and pump casings that is utilized to effect the flow of the working fluid here desired, it is obvious that the present invention is applicable to rotary compressors not so housed or driven so long as a suitable head of pressure for effecting the flow of the working fluid is provided, for example by means of a separately driven circulation pump.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from-the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A rotary compressor having slidable blades forming pump chambers, means for supplying lubricant under pressure behind the blades only at the point of maximum displacement of the chambers, said blades having their leading faces grooved whereby lubricant will be forced from the space behind the blades through said grooved portions into the displacement area of the compressor.

2. A compressor, a motor for driving said compressor, a casing for the compressor, a casing for the motor, the compressor casing being in communication with the high pressure side, the motor casing being in communication with the low pressure side, conduits leading from the motor and compressor bearings into the compressor, said compressor having a slotted driving disk with blades reciprocably mounted therein, means for supplying lubricant under pressure to the space back of the blades only when the pump chamber is at its maximum displacement, the leading faces of the blades being grooved whereby upon reduction of the maximum displacement in the pump chamber such lubricant will be forced from behind the blades, up the leading faces and into the pump chamber.

3. A device of the class described comprising a compressor, a motor for driving the compressor, casings for the compressor and motor in communication respectively with the discharge and suction sides of the compressor, a port on one side of the compressor having communication with the discharge side of the compressor, a port on the opposite side of the compressor having communication with the motor bearings, a transverse slot in the compressor, acompressor blade reciprocating in said slot thereby periodically forming a chamber between the ports on opposite sides of the compressor whereby metered quantities of lubricant under pressure will be supplied therethrough, said slot being arranged to connect said ports only when the chamber of the compressor is at its maximum displacement.

4. A device of the class described comprising a compressor, a motor for driving the compressor, casings for the compressor and motor in communication respectively with the discharge and suction sides of the compressor, a port on one side of the compressor having communication with the discharge side of the compressor, a port on the opposite side of the compressor having communication with the motor bearings, a transverse slot in the compressor, a compressor blade reciprocating in said slot thereby periodically forming a chamber between the ports on opposite sides of the compressor whereby metered quantities of lubricant under pressure will be supplied therethrough, said slot being arranged to connect said ports only when the chamber of the compressor is at its maximum displacement, and means for discharging lubricant from said slot into the chamber as its displacement is decreased.

5. A device of the class described comprising a high pressure chamber and a low pressure chamber, a sliding blade compressor in the high pressure chamber, a motor in the low pressure chamber, a conduit leading from the high pressure chamber to the compressor and motor bearings, the compressor forming a valve for shutting oil? the flow to the motor bearings, and means for supplying lubricant behind the blades of the compressor only when the chamber is at maximum displacement and the blades are in their outermost position.

6. A device of the class described comprising a high pressure chamber and a low pressure chamber, a sliding blade compressor in the high pressure chamber, a motor in the low pressure chamber, a conduit leading from the high pressure chamber to the compressor and motor bearings, the compressor forming a valve for shutting oh the flow to the motor bearings, and means for supplying lubricant behind the blades of the compressor only when the chamber is at maximum displacement and the blades are in their outermost position, and means for efiecting transfer of lubricant from behind the blades to the displacement area of the compressor.

7. A device of the class described comprising a high pressure chamber and a low pressure chamber, a sliding blade compressor in the high pressure chamber, a motor in the low pressure chamber, a conduit leading from the high pressure chamber to the compressor and motor bearings, the compressor forming a valve for shutting off the flow to the motor bearings, and means for supplying lubricant behind the blades of the compressor only when the chamber is at maximum displacement and the blades are in their outermost position, grooves in said blades whereby lubricant may be transferred to the displacement area of the compressor.

8. In combination, a rotary compressor, a casing into which said compressor discharges, a motor for driving said compressor, a conduit leading from said casing into the compressor, a conduit leading from the compressor to the motor bearings, said compressor forming a valve between said conduits for directing measured quantities of lubricant to the motor bearings, said compressor comprising a rotor member having transverse slots therein, compressor blades reciprocating in said slots, means for supplying lubricant under pressure behind the blades only at the point of maximum displacement whereby the backs of the reciprocating blades after passing the point of maximum displacement, cooperating with, the transverse slots, form a pump for forcing lubricant into the bearings of the motor.

. FRANK D. PELTIER. 

